1. Field of Invention
The present invention relates to a method for manufacturing a semiconductor device. More particularly, the present invention relates to a method for forming contact holes.
2. Description of Related Art
Due to the rapid development of integrated circuits, minimizing the device dimension and increasing the integration level have become the mainstream in semiconductor industry, and the key technology is in photolithography. With the increasing of the integration of the semiconductor device, the critical dimension (CD) is decreased. Thus, it is necessary to improve the resolution of the photolithography.
For instance, due to the size reduction, optical properties of material is harder to gauge and the photolithographic process has encountered some machine processing limits and physical limit in optical properties. As a result, the process of fabricating contact holes using photolithographic technique is increasingly difficult.
In order to increase the ability for controlling the critical dimension of the contact holes and decrease the cost, it is necessary to improve the method for forming the contact holes under the conditions of the existing equipments.